1. Field of the Invention
This invention relates to an apparatus for installing rolls on a shaft.
2. Discussion of the Technical Problems and Prior Art
Rollers for conveying sheets, e.g., glass sheets or a glass ribbon include a rigid shaft having a plurality of spaced resilient, flexible, rubber or urethane rolls or O rings often referred to as donut rolls mounted thereon. The rolls are periodically replaced because of (1) wear which reduces the roll diameter and/or (2) cuts and chips resulting from the leading edge of the glass sheets or ribbon running into the rolls. At the present time, worn rolls are removed by cutting through the rolls and new rolls installed on the shaft by hammering the rolls along the shaft into position. The rolls are frictionally held in position by providing the shaft with an outside diameter greater than the inside diameter of the rolls.
The technique of hammering rolls into position is not acceptable because it is time consuming and requires care to properly mount the rolls on the shaft. More particularly, if the plane through which the rolls rotate is not normal to the axial center of the shaft, the moving glass sheet or ribbon shifts toward a side of the conveyor. If the rolls are not properly spaced on the shaft, the glass sheet or ribbon will not be properly supported which could induce cracks in the glass. Although the prior art teaches techniques for mounting articles on members, these techniques are not acceptable for mounting rolls on shafts where the inside diameter of the rolls is smaller than the ouside diameter of the shaft.
U.S. Pat. Nos. 2,008,772; 2,218,904; 3,369,286; 3,611,536 3,665,578; 3,686,741; 3,812,562; 3,827,124 and 3,879,252 each, in general, teach a method of mounting a flexible ring or sleeve on an elongated member, e.g., a shaft by expanding the ring to mount same on the shaft. The expansion may be accomplished by forcing the sleeve onto a mandrel having a tapered surface; by heating the sleeve or expanding the sleeve using air. Although the above techniques are acceptable for their intended purpose they are not readily adaptable for mounting donut rolls on a shaft. This is because the donut rolls are too thick and made of urethane which is not readily expandable to facilitate mounting the rolls on the shaft. In addition some shafts have lengths of up to about 180 inches (4.5 meters) and to maintain the donut rolls in the expanded condition while moving same over the shaft is not feasible. Further, applying sufficient pressure to expand the inside surface of the roll may damage the roll reducing the required friction to secure the rolls in position. When this occurs the roll is not driven by the shaft but slips and will not advance the glass sheet or glass ribbon.
U.S. Pat. No. 3,426,119 teaches a technique for mounting a heat shrinkable sleeve on a shaft. This technique is not acceptable because the donut rolls employed for conveying the sheets are not heat shrinkable as required to practice the technique of the above-mentioned patent.
U.S. Pat. No. 2,658,269 teaches the mounting of rubber bushings on a sway bar by clamping the sway bar and forcing the bushing along the bar using a piston and cylinder arrangement. This technique is not acceptable for mounting donut rolls on shafts because the thickness of the donut rolls and the difference between the inside diameter of the donut roll and outside diameter of the shaft requires a force of such magnitude that is is not easily provided by a piston and cylinder arrangement. Further, using a piston and cylinder arrangement would require an unusually long one e.g., a piston and cylinder arrangement having a extended length of 360 inches (9 meters) for mounting rolls on a shaft 180 inches (4.5 meters) long.
Although the above prior art techniques for mounting O rings, sleeves, and/or bushings on shafts are acceptable for their intended purpose, they are not adaptable for mounting donut rolls on shafts for the reasons discussed above. Therefore, it would be advantageous to provide an apparatus for mounting donut rolls on a shaft that does not have the limitions of the prior art.